[PATCH 5.10 297/406] X.509: if signature is unsupported skip validation

Greg Kroah-Hartman
2023-09-17T19:37:31Z

From: Thore Sommer <public@thson.de>

commit ef5b52a631f8c18353e80ccab8408b963305510c upstream.

When the hash algorithm for the signature is not available the digest size
is 0 and the signature in the certificate is marked as unsupported.

When validating a self-signed certificate, this needs to be checked,
because otherwise trying to validate the signature will fail with an
warning:

Loading compiled-in X.509 certificates
WARNING: CPU: 0 PID: 1 at crypto/rsa-pkcs1pad.c:537 \
pkcs1pad_verify+0x46/0x12c
...
Problem loading in-kernel X.509 certificate (-22)

Signed-off-by: Thore Sommer <public@thson.de>
Cc: stable@vger.kernel.org # v4.7+
Fixes: 6c2dc5ae4ab7 ("X.509: Extract signature digest and make self-signed cert checks earlier")
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
crypto/asymmetric_keys/x509_public_key.c | 5 +++++
1 file changed, 5 insertions(+)

--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -132,6 +132,11 @@ int x509_check_for_self_signed(struct x5
if (strcmp(cert->pub->pkey_algo, cert->sig->pkey_algo) != 0)
goto out;

+ if (cert->unsupported_sig) {
+ ret = 0;
+ goto out;
+ }
+
ret = public_key_verify_signature(cert->pub, cert->sig);
if (ret < 0) {
if (ret == -ENOPKG) {